Monofilament dental tapes traditionally have focused on improving their primary consumer benefits of reduced xe2x80x9cshreddingxe2x80x9d and reduced breakage during flossing while falling short on a range of product attributes generally associated with various releasable coatings applied to these monofilament tapes. These coating-related attributes included: hi-impact flavor, mouth feel, cleaning and xe2x80x9chandxe2x80x9d of the coated tape. These attributes generally require coatings at from between about 20% by weight of the monofilament tape and about 120% by weight of the tape.
Monofilament interproximal devices are described and claimed in: U.S. Pat. Nos. Re 35,439; 3,800,812; 4,974,615; 5,760,117; 5,433,226; 5,479,952; 5,503,842; 5,755,243; 5,845,652; 5,884,639; 5,918,609; 5,962,572; 5,998,431; 6,003,525; 6,083,208; 6,148,830; 6,161,555; and 6,027,592, the disclosures of which are hereby incorporated herein by reference. These dental tapes generally have serious shortcomings in gentleness, in delivering coatings during flossing and in being handled easily and conveniently during flossing.
Polytetrafluoroethylene (PTFE) based interproximal devices are described in: U.S. Pat. Nos. 5,209,251; 5,033,488; 5,518,012; 5,911,228; 5,220,932; 4,776,358; 5,718,251; 5,848,600; 5,878,758; and 5,765,576. To date, no commercial versions of these tapes have been coated effectively and cannot be used to deliver active ingredients, interproximally and subgingivally during flossing. Handling during flossing is difficult. Most have to be folded to provide a consumer acceptable edge. Many are plagued with serious dimensional inconsistency problems, as well.
Most monofilament tapes and particularly the PTFE tapes are difficult to coat with xe2x80x9creleasable coatingsxe2x80x9d at these relatively high levels, particularly when the coatings are required to be substantially free from flaking. Copending Provisional Application Serial No. 60/263,220 is directed to crystalline-free releasable coatings for PTFE and other monofilament tapes that are substantially free from flaking. The teachings of this application are incorporated herein by reference.
Heretofore, coatings for dental flosses and dental tapes have traditionally been comprised of microcrystalline wax and a small amount of flavor. Occasionally trace amounts of xe2x80x9cactive ingredientsxe2x80x9d such as fluoride, CPC or triclosan are added. The content of each of these additives in the coating is limited to the solubility of the desired ingredients in the wax. An additional limitation of this traditional coating approach is that the flavor remains trapped inside the wax and is not available to the oral cavity or interproximal spaces during flossing. Even if the wax is mechanically removed from the floss or tape by flossing very little of the wax-trapped ingredient content makes contact with the oral cavity. In spite of the great sensitivity of taste buds and olfactory nerves, these xe2x80x9ctrappedxe2x80x9d flavors are barely perceptible.
Hill et al. disclose a series of coating agents for multifilament dental flosses as distinguished from monofilament tapes (see U.S. Pat. Nos. 4,911,927; 5,057,310; 5,098,711; 5,165,913 and 5,711,935). These coating agents basically rely on emulsifiable ingredient consisting of a suitable surfactant, such as a poloxamer (Pluronic F-127) and a xe2x80x9ccoating agentxe2x80x9d which is insoluble in, but emulsifiable by the surfactant in its molten state. These coating agents are typically very non-polar materials such as silicones (PDMS) or microcrystalline paraffin waxes. The teachings of the Hill, et al. patents are incorporated herein by reference.
Despite the utility of the Hill et al. coatings, their multi-functionality and commercial use in major brands and specialty professional multifilament flosses, the greatest draw-back of these melt-emulsion systems is the inherent viscosity characteristic of any emulsion, especially melt emulsions. These high viscosities necessitate a manufacturing process requiring specialized equipment to force the high viscosity melt either down into the multifilaments of the floss by means of xe2x80x9ccompression loadingxe2x80x9d.
There are also many references and commercial embodiments of the use of so-called water soluble waxes, primarily high molecular weight polyethylene glycols (PEGs), to coat dental flosses and tapes. The primary function of the PEG is to serve as a saliva soluble carrier for small amounts of flavor and other additives. The advantage of a PEG coating is that its melt viscosity is low and low levels of coating can be added with very simple mechanisms requiring little need for attention by an operator. The most common of these is a simple rolling wheel, the lower one-third of which is immersed in the molten PEG, and the floss or tape is pulled across the top of the wheel, thereby picking up a small quantity of the molten PEG coating agent.
There are many shortcomings of the simple water-soluble wax (PEG) coated flosses and tapes. Among them:
(1) melt solutions of block copolymers and non-ionic surfactant polyethylene glycols in ratios from between about 80:20 and about 20:80;
(2) The products lack surfactancy, i.e. the ability to clean in the interproximal spaces;
(3) The products have low coating loads due to the poor adhesion, or if thick layers or loads are applied, they bind poorly to the tape or filament surfaces and flake off easily in product manufacture, packaging and consumer use;
(4) The products use water soluble waxes which will solubilize in only a limited range, or limited quantities, of ingredients, since it has no polarity or surfactant properties;
(5) The products have no ability to promote a pleasant mouth feel as do the coatings references in the Hill et al. patents.
The present invention is directed to substantive coatings for monofilament tapes that are neither described nor suggested by the noncrystalline coatings described in copending Provisional Patent Application Serial No. 60/263,220. These substantive coatings for monofilament tapes comprise:
(1) solutions of block copolymers and non-ionic surfactant polyethylene glycols in ratios from between about 80:20 and about 20:80;
(2) melt emulsions of chemotherapeutic ingredients coated on the tape at from between about 30 and 120 mg/yd containing a high percentage of surfactants as the continuous phase and a surface energy modifying level of a wax as the discontinuous phase including: microcrystalline, petroleum, bees wax, polyethylene, carnauba other natural waxes and combinations thereof; and
(3) inverse melt emulsions of surfactant in a continuous phase of wax, where the ratio of wax to surfactant is from between about 99:1 and about 60:40.
One preferred embodiment of the present invention comprises the various substantive coatings for monofilament dental tapes described herein.
Other preferred embodiments of the invention comprise the various processes for coating monofilament dental tapes with substantive coatings described herein.
A further preferred embodiment of the invention comprises the monofilament dental tapes which include a wide range of substantive coatings, as taught herein.
These and other embodiments of the invention are described in detail below.
A: Monofilament Tape Coatings Comprising Solutions of Block Copolymers and Nonionic Surfactant Polyethylene Glycols:
It has been found that certain melt solution coated monofilament dental tapes of the present invention surprisingly have a high level of flavor released when flossing, and furthermore, exhibit unexpected flexibility and attachment during subsequent winding steps. Block co-polymers, such as Pluronic F-127, are formulated in a range of from 48 to 90 percent by melting along with 47 to 7 percent by weight of the non-ionic surfactant polyethylene glycol 1450. Flavors are utilized from 2 to 17 percent by weight.
The melt solution coated monofilament dental tapes of the present invention surprisingly have a high level of flavor released when flossing, while exhibiting unexpected flexibility and attachment during subsequent winding steps. In contrast, coatings utilizing a single non-ionic surfactant have exhibited less than desirable retention on the dental tape with extensive flaking off.
A general purpose xe2x80x9cchemical basexe2x80x9d is first formed from a melt solution of a water-soluble wax (PEG or similar substances) and a PEG-soluble surfactant (such as a poloxamer typified by Pluronic F-127 supplied by BASF). This is made by melting and combining the two ingredients with a ratio ranging from 90:10 to 10:90. Preferably, the ratio of PEG to surfactant ranges from 80:20 to 20:80. The range will vary dependent upon the nature and chemistry of the other ingredients required, the flexibility of the finished coating desired, and the processing equipment chosen. Dental flosses and dental tapes will also require different variations within the specified ranges to accommodate the different surface free energies and surface areas.
To the above solution or xe2x80x9cchemical basexe2x80x9d, one or more of the following multi-functional ingredients are added. The value of this invention is seen in the increased quantities, number of ingredients and variety of chemistries accommodated by the unique solution of neutral and surfactant water-soluble polymers.
(1) Mouth feel agents such as carboxy methyl cellulose (CMC), hydroxypropylcellulose, natural gums, resins and the like;
(2) Flavoring and sweetening agents;
(3) Soft abrasives which are suspendable in the low viscosity solutions, including silica gels, porous calcium carbonates, and natural abrasives such as rice flours, bran, corn powders, and the like;
(4) Antimicrobials such as CPC, triclosan, metronidazole, chlorhexidine digluconate, and the like;
(5) Fluoride sources such as Sodium Fluoride, Stannous Fluoride, and the like;
(6) Tartar control agents;
(7) NSAIDs and MMP inhibitors;
(8) Soluble emulsifying agents such as ethylene vinyl alcohol copolymers or other copolymers soluble in the xe2x80x9cchemical basexe2x80x9d;
(9) Colorants and opacifiers.
This embodiment of the present invention will be further illustrated with reference to Examples 1 and 2 which will aid in the understanding of the present invention, but which are not to be construed as limitations thereof. All percentages reported herein, unless otherwise specified, are percent by weight. All temperatures are expressed in degrees Celsius.